JPH11277918A - Thermal transfer image receiving sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high quality transfer images, and render photographic printing sensitivity excellent by employing a base material of plain paper, and specifying a substantial thickness of a dye receptor layer. SOLUTION: When the substantial thickness of a dye receptor layer 3 is less than 7 μm, it is affected by an influence of the surface unevenness caused by a pulp shape of plain paper being a base material, resulting in no fulfillment of a sufficient photographic printing quality and photographic sensitivity. Also, when the substantial thickness of the dye receptor layer is more than 7 μm, both the photographic printing quality and the photographic printing sensitivity are satisfied together so that the upper limit is not restricted in particular, but when the dye receptor layer becomes thicker than being required, since costs increase, the substantial thickness is preferable to be 30 μm. The substantial thickness can be obtained by measuring substantially the thickness of plain paper being a base material before coating and the thickness of a thermal transfer image receiving sheet after forming the dye receptor layer through coating and fixing of powder components. Besides of an interior part of the dye receptor layer is a noncontinuous film layer with voids, cracks, or the like formed therein, it is available with a thickness of 7 μm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer image-receiving sheet used in combination with a sublimation type thermal transfer sheet.
The present invention relates to a thermal transfer image-receiving sheet having a dye receiving layer formed on plain paper using a powder composition, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as an image receiving sheet of a thermal transfer recording system using a sublimable dye, a composition containing a resin having a dye-dyeing property is coated on the surface of a base sheet such as synthetic paper, and dried to form a dye. Those formed with a receiving layer are known.

Conventionally, a solvent-type coating composition has been used for the dye-receiving layer, but in recent years, it has been proposed to use a powder coating composition as the composition of the dye-receiving layer (see, for example, Japanese Patent Application Laid-Open No. Hei 8 (1996)). -112974, JP-A-8-224970
No.).

This powder coating composition is prepared by melting and kneading a composition containing a resin component, a white colorant, a charge controlling agent, an anti-offset agent, etc., cooling and pulverizing the mixture so as to have an appropriate average particle size. It is classified. Manufacture of the image receiving sheet, after the powder coating composition is adhered to the surface of a sheet serving as a base material such as plain paper by a method such as an electrostatic powder coating method, and then heated, pressed or heated and pressed. Fix to form a dye receiving layer. The image receiving sheet has features such as a simple manufacturing process and a simple layer configuration.

[0005]

However, when a dye-receiving layer is formed using a powder coating composition, a dye-receiving layer is formed on the surface of synthetic paper or the like using a solvent-type coating composition to receive an image. It has been found that there are various problems unlike the case of manufacturing a sheet.

That is, since the powder coating composition is applied to the surface of the base material in the form of a powder, voids and the like are present between the powders. Even after the formation, a complete continuous film is not obtained, and fine gaps and voids are present. Further, when the powder coating is applied to the surface of a porous substrate such as plain paper, the coating composition penetrates into the gaps of the pulp. Then, the applied powder coating material further penetrates into the inside of the base material by heating and pressurizing during fixing.

As described above, when a powder composition is applied to the surface of plain paper to form a dye-receiving layer, the actual amount of the dye-receiving layer is kept constant even when the coating amount is fixed as in the conventional coating. The thickness is not formed to a certain thickness corresponding to the coating amount, and the dye receiving layer is strongly affected by surface irregularities derived from the shape of the pulp of plain paper, etc., stably ensuring sufficient printing image quality and printing sensitivity. Could not be obtained.

[0008] The present invention has been made in view of the above problems, and in a thermal transfer image receiving sheet having a dye receiving layer formed from a powder composition, a high quality transfer image can be obtained and printing sensitivity is good. It is an object of the present invention to provide a thermal transfer image-receiving sheet having a stable dye-receiving layer and a method for producing the thermal transfer image-receiving sheet stably.

[0009]

SUMMARY OF THE INVENTION The present invention relates to (1) a thermal transfer image-receiving sheet having a dye-receiving layer formed from a powder composition mainly composed of a dye-dyeable resin on at least the substrate. Is a plain paper and the substantial thickness of the dye receiving layer is 7 μm or more,
(2) A powder composition mainly composed of a dye-dyeable resin is applied to the surface of a substrate made of plain paper, and the coated product is fixed on the surface of plain paper to form a dye-receiving layer, and is thermally transferred. In the method for producing an image receiving sheet, the substantial thickness of the dye receiving layer after fixing is 7
A method for producing a thermal transfer image-receiving sheet, characterized in that fixing is performed so as to be at least μm.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, a thermal transfer image-receiving sheet 1 of the present invention has a thermal transfer image having at least a dye receiving layer 3 formed from a powder composition mainly composed of a dye-dyeable resin on a base material 2 made of plain paper. An image receiving sheet, wherein the substantial thickness of the dye receiving layer is formed to be 7 μm or more.

The substantial thickness of the dye receiving layer 3 is the actual thickness of the dye receiving layer 3 after fixing. In general, when a resin layer is formed by applying a solvent-based coating composition on the surface of a plastic film or the like that does not seep, there is no generation of voids or cracks inside the resin layer and the inside of the film is coated. Assuming that the coating composition does not penetrate and only the solvent volatilizes to form a layer and a film is continuously formed, the thickness of the resin layer is actually calculated as represented by the following [Equation 1]. Can be determined from the amount of application and the density without measuring the thickness.

[0012]

## EQU1 ## Thickness of coating layer (μm) = Amount of coating per unit area (g / m ² ) / Powder composition density (g / cm ³ )

However, actually, when the powder composition 4 is applied and fixed on the surface of the substrate 2 as shown in FIG.
When a coating layer made of a powder composition is heated and pressurized during fixing to melt the powder particles to form a film, it is completely melted to form a uniform continuous film layer. Instead, as shown in FIG. 2 (b), there are voids 5 or cracks inside. When plain paper is used as the base material, a layer having a thickness of SA is formed inside the paper, for example, by the powder composition penetrating into the gaps of the pulp of the paper. The thickness of the dye-receiving layer formed from the powder composition in this way depends on the heating conditions or pressure conditions during fixing, the type of plain paper, the composition of the powder composition, etc. It does not become as shown in the formula [Equation 1] determined from the relationship between the amount and the density of the coating composition.

The substantial thickness (CA) of the dye receiving layer is obtained by subtracting the base material thickness (BA) from the total thickness (TA) as represented by the following equation (2).

[0015]

## EQU2 ## Coating layer thickness CA (μm) = total thickness TA (μ
m) -Substrate thickness BA (μm) In the above [Equation 2], the total thickness and the substrate thickness both use the values actually measured. In the case of the receiving layer formed from the powder composition, the present inventors have determined that the substantial thickness (C
A) was found to greatly affect printing performance such as printing quality and printing sensitivity.

If the substantial thickness of the dye-receiving layer 3 is less than 7 μm, it is strongly affected by surface irregularities derived from the pulp shape of the plain paper as a base material, and sufficient printing quality and printing sensitivity cannot be realized. In addition, if the substantial thickness of the dye receiving layer is 7 μm or more, the image quality and the printing sensitivity are satisfied, so that
The upper limit is not particularly limited, but if the dye-receiving layer is unnecessarily thick, the cost increases, and the substantial thickness is 30 μm.
It is preferred that m be the upper limit.

The substantial thickness of the dye-receiving layer is determined by the thickness of the plain paper as the base material before coating and the thickness of the thermal transfer image-receiving sheet after coating and fixing the powder composition to form the dye-receiving layer. It can be determined by actually measuring. The inside of the dye receiving layer may be a discontinuous coating layer in which voids, cracks, and the like are formed, as long as the measured thickness is 7 μm or more. In order to make the thickness 7 μm or more, 1) the coating amount of the powder composition is set to a certain value or more. 2) The heating temperature and the pressing pressure are adjusted to melt the powder composition and permeate the plain paper. And the like.

As the plain paper used as the base material 2, a paper mainly composed of pulp which is usually used is used. Examples of the plain paper include high-quality paper, art paper, lightweight coated paper, lightly coated paper, coated paper, cast coated paper, synthetic resin or emulsion impregnated paper, and the like. The thickness of plain paper is 40 ~
It is about 300 μm, preferably about 60 to 200 μm.
In order to give the resulting thermal transfer image-receiving sheet a high texture of plain paper, the total thickness of the thermal transfer image-receiving sheet should be 80-200.
It is desirable to make it about μm.

The dye receiving layer 3 is formed from a powder composition mainly composed of a dye-dyeable resin. In the powder composition, in addition to the dye-dyeable resin, a release agent for preventing the dye receiving layer from fusing with the thermal transfer sheet, and a charge control agent for controlling the chargeability of the powder coating. And a white colorant for imparting hiding power, an anti-offset agent, a flow improver, and the like.

The dye-dyeable resin includes, for example, saturated polyester resin, polyamide resin, polyacrylate resin, polycarbonate resin, polyurethane resin, polyvinyl acetal resin, polyvinyl chloride resin, polyvinyl acetate resin, polystyrene resin, styrene-acrylic resin. Resin, styrene-butadiene copolymer resin, vinyl chloride-vinyl acetate copolymer resin, vinyl toluene-acryl resin, cellulose resin and the like. These resins are
They can be used alone or in combination of two or more.
The amount of the dye-dyeable resin is 70% by weight in the powder composition.
If it is less than 70%, the dye-dyeing property is not sufficiently exhibited, and the printing sensitivity may be lowered. Therefore, it is preferable to use 70% by weight or more of the powder composition.

As the release agent, silicone oil, phosphate ester plasticizer, fluorine compound, various waxes and the like can be used, but silicone oil is preferable. As the silicone oil, epoxy-modified, alkyl-modified, amino-modified, carboxyl-modified, alcohol-modified, fluorine-modified, alkyl aralkyl polyether-modified, epoxy-polyether-modified, polyether-modified silicone oils are preferably used. Preferred are a reaction product of a vinyl-modified silicone oil and a hydrogen-modified silicone oil, and a reaction cured product of an amino-modified silicone and an epoxy-modified silicone, or a modified silicone having active hydrogen and a curing agent that reacts with active hydrogen. The hardener having active hydrogen is preferably a non-yellowing type isocyanate compound, specifically, XDI, hydrogenated XDI, TMXDI, HDI, IPDI, and their respective adducts / vullets, oligomers, and prepolymers. As wax, melting point is 50-150 ° C
Preferred are, for example, liquid or solid paraffin, polyethylene, polyolefin wax such as polypropylene, aliphatic metal salts, fatty acid esters, partially saponified fatty acid esters, higher fatty acids, higher alcohols,
Examples include silicone varnish, amide wax, aliphatic fluorocarbon and modified products thereof. The addition amount of the release agent is based on 100 parts by weight of the resin forming the dye receiving layer.
0.2 to 30 parts by weight is preferred.

The charge control agent is for controlling the charge polarity and the charge amount of the powder composition, and those used for a conventionally known toner for developing an electrostatic latent image can be used. Examples of negative charge control agents include 2: 1 type metal-containing azo dyes, metal complexes of aromatic oxycarboxylic acids and aromatic dicarboxylic acids, sulfonylamine derivatives of copper phthalocyanine dyes and sulfonic acid amide derivatives of copper phthalocyanine Dyes and the like. Further, as a positively chargeable charge control agent,
For example, in addition to a quaternary ammonium compound, an alkylpyridinium compound and an alkylpicolinium compound, various nigrosine dyes can be used. The addition amount of the charge control agent is 0.1 to 1 with respect to 100 parts by weight of the resin of the dye receiving layer.
The amount is preferably 0 parts by weight, particularly preferably 0.3 to 5 parts by weight.

The white colorant is for imparting hiding power and whiteness to the dye receiving layer, and examples thereof include calcium carbonate, talc, kaolin, titanium oxide, zinc oxide and the like. The amount of the white colorant to be added depends on the resin 10 of the dye receiving layer.
The amount is preferably 10 to 200 parts by weight with respect to 0 parts by weight. If the amount of the white colorant is less than 10 parts by weight, the effect of adjusting the color tone is poor, and if it exceeds 200 parts by weight, the dispersion stability in the dye receiving layer is reduced, and the performance of the resin in the dye receiving layer is sufficiently obtained. It may not be possible.

The fluidity adjusting agent is used to enhance the fluidity of the powder composition, and examples thereof include hydrophobic silica.

The pigment composition for the dye receiving layer contains various pigments,
Coloring materials such as dyes and fluorescent whitening agents can be included. When a thermal transfer image receiving sheet is used as a proofreading output material for printing proofreading, and when the color tone is matched with the corresponding printing paper, a desired color tone can be obtained by appropriately blending these colorants in the powder composition.

The preferred color tone of the surface of the dye receiving layer is in the following range.

[Outside 1] Since a dye is used for sublimation transfer, the color tone of the print is affected by the color tone of the surface of the receiving layer. By correcting the applied energy during dye transfer according to the color tone of the receiving layer surface of the image receiving sheet to be used, the above effect can be avoided.However, when the color tone is out of the above range, adjustment becomes difficult, and good visual texture is obtained. I can't. The following range is more preferable for obtaining a high quality paper-like texture.

[Outside 2]

The powder composition of the dye receiving layer is mainly composed of the dye-dyeing resin described above, mixed with other additives, melted, kneaded, uniformly dispersed, cooled, and pulverized. After that, it is obtained by classifying as necessary to obtain a desired average particle size. The average particle size of the powder coating composition is from 1 to 30.
μm is preferred, and more preferably 5 to 15 μm.

It is preferable to use a plain paper base material having a surface tone close to that of a desired image receiving sheet. This is the case where the color tone of the substrate is transparent even if the color tone of the receiving layer formed by applying and fixing the powder composition is adjusted, and as a result, the color tone of the surface of the receiving layer is different from the desired one. Because there is. It is preferable that the color difference ΔE between the surface color tone of the base material and the desired surface color tone of the receiving layer is formed by the following equation (3).

[Equation 3] ΔE ≦ 3

The method for producing a thermal transfer image-receiving sheet of the present invention comprises:
On the surface of a base sheet made of plain paper, the above powder composition mainly composed of a dyeable resin is applied, and heated, pressed, or fixed by heating and pressing to form a dye receiving layer. To produce a thermal transfer image receiving sheet. The coating of the powder coating composition can be performed by an electrophotographic method or an electrostatic powder coating method.

The electrophotographic method is based on the same principle as an electrophotographic copy machine or a laser printer, and the powder coating composition (toner) is charged by friction charging or the like, and the powder coating composition (toner) is charged on the drum surface charged to the opposite polarity. Attach it by attractive force.
Further, the method is such that the toner adhered to the drum surface is transferred onto the surface of plain paper as a base material, and is heated and fixed. The drum is formed from an organic photoconductor or the like, and is charged by corona charging or the like.
A portion of the drum surface, which is to be a desired image, is neutralized by light irradiation to create a so-called electrostatic latent image, a powder coating is adhered to the latent image, transferred, and fixed to form a dye receiving layer only on the desired portion. You can also.

In the electrostatic powder coating method, the powder paint is conveyed to an electrostatic spray gun by an air stream and charged, and the powder paint is sprayed from the electrostatic spray gun on the surface of grounded plain paper. Adheres to plain paper surface by electrostatic attraction. The electrostatic spray gun has a needle-shaped or ring-shaped corona electrode near the tip of the outlet, and the electrode has a shape of -20.
A voltage of about kv to +80 kv is applied. Further, the powder coating material can be stirred in the container and frictionally charged by friction with the inner wall surface of the container. The powder paint adhering to the plain paper surface
After being heated and melted by infrared rays or the like, the dye-receiving layer is formed by fixing. Heating and pressurizing or heat and pressurizing is used for fixing the dye receiving layer.

In the production method of the present invention, the powder composition is fixed so that the thickness CA of the dye receiving layer after fixing shown in FIG. 2 (b) is 7 μm or more. The fixing means for controlling the thickness of the dye-receiving layer to 7 μm or more depends on the type and density of the powder composition of the dye-receiving layer, the type of plain paper as the base material, and the like, the amount of coating, the heating temperature, and the pressure. By adjusting the pressure and the like, it is possible to control the amount of permeation into the base material or the ratio of voids when the powder composition is melted. Heating means for fixing the dye receiving layer includes indirect heating using warm air, infrared rays, microwaves, or the like, or direct heating using a hot roll or a hot plate. Further, as the pressing means, a roll, a plate or the like can be used.

As shown in FIG. 3, for example, a specific manufacturing apparatus is provided with a roll 11 for supplying plain paper, a hand gun 12, and the like, and is provided with an electrostatic coating for applying the powder composition to the surface of the plain paper. It can be constituted by a device 13, a fixing device 14 having a pressurizing and heating roller, a cooling device 15, a winding device 16 for winding the thermal transfer image receiving sheet, and the like.

When a thermal transfer image receiving sheet is used, a sublimation type thermal transfer sheet used in a sublimation transfer recording system is used as the thermal transfer sheet. Application of thermal energy at the time of thermal transfer can use a known means, for example,
An image can be formed by applying a thermal energy of about 5 to 100 mj / mm ² by controlling the recording time with a recording device such as a thermal printer (for example, a printer Rainbow M2720 manufactured by 3M).

[0035]

Embodiments of the present invention will be described below. Example 1 After mixing a powder composition raw material having the following composition with a mixer,
The mixture was heated and melted and kneaded by a melt kneader. Cooling the mixture,
After coagulation, the mixture was pulverized and classified to obtain a powder composition having an average particle size of 8 μm. 2 parts by weight of hydrophobic silica (RA-20, manufactured by Nippon Aerosil Co., Ltd .: 100 parts by weight of this powder composition)
0H) to obtain a powder composition for use in the dye-receiving layer.

[Powder composition raw material composition (all units are parts by weight)] ・ Polyester resin (Mitsubishi Rayon Co., Ltd .: Diacron FC-611) 80 parts ・ Styrene-acrylic resin (Mitsubishi Rayon Co., Ltd .: FB-206) 20 parts ・ Charge control agent (Orient Chemical: Bontron P-51) 4 parts ・ Titanium oxide (Tochem Products: TCA888) 2 parts ・ Amino-modified silicone (Shin-Etsu Chemical: X22-349) 1 part Epoxy-modified silicone (KF-393 manufactured by Shin-Etsu Chemical Co., Ltd.) 1 copy

The above-mentioned powder coating was applied to one surface of high-quality paper having a basis weight of 104.7 g as a substrate by using the following electrostatic coating method.
Coating was performed at 0 g / m ² (solid content). This was heated and pressurized and fixed using a hot roll under the following conditions to form a dye receiving layer to obtain a thermal transfer image receiving sheet. When the thickness of the high-quality paper was measured (measurement machine, manufactured by Sony: μMate), it was 93 μm.

[Electrostatic powder coating method] ・ Electrostatic powder coating apparatus: GX, manufactured by Nippon Parkerizing Co., Ltd.
5000S ・ Hand gun: GX106, manufactured by Nippon Parkerizing Co., Ltd.
N

[Fixing conditions] Heat roll diameter: 40 m in diameter on both the dye receiving layer side and the back side
m · Heating temperature: 140 ° C for both rolls · Roll speed: 20 mm / min · Pressing pressure: 2 kg per roll length 25 cm · Roll surface roughness (Ra): 0.5 µm for both rolls · Roll mirror gloss (Gs45 °) ): 8.0%

Examples 2 to 6 and Comparative Examples 1 to 3 Thermal transfer image-receiving sheets were obtained in the same manner as in Example 1 except that the amount of the powder coating applied or the fixing conditions were as shown in Table 1 below.

Further, the total thickness of the thermal transfer image-receiving sheets of the above Examples and Comparative Examples was measured to determine the thickness of the dye receiving layer.
Printing was performed using a sublimation transfer printer “Rainbow 2720” manufactured by M Corporation and a dye transfer film for the printer, and the print quality and print sensitivity were evaluated. Table 1 shows the measurement results and the evaluation results. In addition, each evaluation method is as follows.

[Print quality] Bk single color density (25% / 10
0%) Bk single color (10%) of solid, 1 dot and 2 dot width
0% / 100%) Fine line, Bk single color (100% / 100%)
%) A character image was prepared and subjected to printing and image evaluation. The print image quality was visually evaluated by sensory evaluation according to the following evaluation criteria. ：: good without missing prints, fine lines, etc. Δ: Slight printing missing, fine line blurring. X: Print missing, fine line fading is remarkable.

[Printing Sensitivity] Mg single-color solid image (70% /
100%) and subjected to printing and sensitivity evaluation. The printing sensitivity was measured by GRETAG SPM50 and evaluated according to the following evaluation criteria. ：: OD value 0.9 or more △: OD value 0.8 or more and less than 0.9 ×: OD value less than 0.8

[0044]

[Table 1] * 1: The temperature of the fixing condition is the upper and lower roll temperatures, and both rolls have the temperatures in the same table.

[0045]

As described above, the thermal transfer image-receiving sheet of the present invention uses plain paper as the base material and is constituted so that the substantial thickness of the dye-receiving layer is 7 μm or more, so that a high-quality transfer image can be obtained. As a result, a thermal transfer image-receiving sheet having a dye receiving layer formed from a powder composition and having good printing sensitivity and stable quality can be obtained.

Further, in the method for producing a thermal transfer image-receiving sheet of the present invention, a powder composition mainly composed of a dye-dyeable resin is coated on the surface of a base material made of plain paper, and the coated product is coated on a plain paper surface. In the method of fixing the dye receiving layer to form a dye receiving layer, a method of fixing the dye receiving layer so that the substantial thickness of the dye receiving layer after fixing is 7 μm or more is adopted, so that the transferred image has high quality and printing sensitivity is low. A good thermal transfer image-receiving sheet can be obtained easily and reliably.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one example of a thermal transfer image-receiving sheet of the present invention.

FIGS. 2 (a) and 2 (b) are process diagrams for explaining a method for producing a thermal transfer image-receiving sheet of the present invention, and FIG. 2 (a) shows a state where a powder composition is applied on a substrate; (B) shows the thermal transfer image receiving sheet after fixing.

FIG. 3 is a schematic view showing an example of a thermal transfer image receiving sheet manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal transfer image receiving sheet 2 Substrate made of plain paper 3 Dye receiving layer

Claims (2)

[Claims] 1. A thermal transfer image-receiving sheet having a dye-receiving layer formed from a powder composition mainly composed of a dye-dyeable resin on at least a substrate, wherein the substrate is plain paper and substantially the same as the dye-receiving layer. A thermal transfer image-receiving sheet having a thickness of 7 μm or more. 2. A base material made of plain paper is coated with a powder composition mainly composed of a dye-dyeable resin, and the coated product is fixed on the surface of plain paper to form a dye receiving layer. A method for producing a thermal transfer image-receiving sheet, comprising fixing the dye-receiving layer such that the substantial thickness of the dye-receiving layer after fixing is 7 μm or more.